Ankle anatomy is complex: each has three bones and 10 tendons, including the Achilles tendon, the thickest and strongest tendon in the ankle. Still, it never captured research attention like the knee and hip, which are replaced in almost 900,000 people per year. Accordingly, past ankle replacement procedures — about 1,000 per year — were based on knee and hip technology.

“The majority of ankle replacements in the 1980s failed because people didn’t appreciate the difference of the ankle anatomy compared to knee and hip anatomy,” says Dr. Brian Donley, vice chair of the department of orthopaedic surgery at Cleveland Clinic.

Working with an international team, Donley won FDA approval last November for the Salto Talaris prosthesis. He was the first doctor in the country to implant the ankle replacement in December.

Available in three sizes, it is made of polyethylene and chromium alloy (essentially, plastic and metal). The prosthesis has two parts: one that attaches to the talus bone in the leg, and one that is fused to the talis at the top of the ankle. The top part resembles a square-bottomed stamp; it can roll along the curved top of the lower joining piece, which allows for circular ankle movement.

Donley is one of three U.S. surgeons on the international research team that developed this technol-ogy. Because the prosthesis is a close replica of the anatomic ankle, doctors can use a smaller incision and remove less bone from the ends of the talis at the top of the ankle, and the tibia, which connects the leg to the ankle.